Ihave E-500 and i tried numerous times to take a snap with persons in front and a building in back (Approximately 200 feet). But i am getting the image with either the person or the Building clearly. I am not able to get both clear. Please advise.

That's normal. What you are experiencing is something known as limited "depth of field". The fact is, depending on the settings, and how you aimed the camera, it will either focus on the person, or it will focus on the building.

The degree to which your photo will have either very narrow depth of field, or wide, is a function of the setting on your camera known as the aperture, or f-stop. This is the iris that exists inside your lens that governs how much light gets let into land on the sensor. There is a second function, known as the shutter speed, which also governs the amount of light, but the shutter works by governing the DURATION that the light is allowed to strike the sensor when the photo is taken - while the aperture governs how wide the light path is through the lens during the period that the photograph is being taken.

Your camera will use it's light meter to determine how much light is needed for a correct exposure, and depending on the setting you use it will let you set the shutter speed (in S mode) or the aperture (in A mode) and it will adjust the other one to expose the photo properly. If you set the camera in Program (or P mode) the camera will make a guess and set both the shutter and aperture to medium values. But it won't know that you are trying to focus on BOTH a nearby person, and a far away building. The way to achieve this is for YOU to set the aperture to a small opening (which, confusingly, is represented by a BIG number, like f11, f16, or f22). These small openings in the lens aperture, represented by the big numbers, will give you the MAXIMUM depth of field (or the range of the photo that is in sharp focus). The bigger the f-number, the broader the depth of field, or area of the photo that will be in focus. The smaller f-numbers (such as f2.8, f3.5, f4, or f5.6) represent wider openings of the lens aperture, and they result in the most narrow depth of field. You would use these f-numbers when you want ONLY the specific subject to be in sharp focus, and everything in the background or foreground to be blurry. This is what you are experiencing now. Many times, photographers use this effect intentionally, because it draws the viewer's interest onto the subject of the photo, and away from the background, which may be distracting.

It's important to realize that, when you change one of the settings (aperture, or shutter speed), you are altering the amount of light that is being allowed to make the exposure, and you (or your camera in one of the automatic modes) will need to change the other setting in the opposite direction to correct the amount of total light being made in the exposure. So, when picking a bigger lens opening, you need to have a faster shutter speed to compensate for it (or vice versa).

I suggest that you experiment with your camera set into A (aperture priority mode) and set the lens f-number to f16. Now, you should find that you have wider depth of field, and both the person and the background will probably both be in focus. But you will probably need to hold your camera steady, because when shooting big f-numbers, you need slower shutter speeds, which make the photo more susceptible to motion blur if you don't hold it steady for the entire duration of the exposure.

BTW, there is nothing wrong with the photos you attached here - they are very nice. I actually think that the first close-up of the flower and the airplane are BETTER photos because the background is NOT in focus, just the subject is. In fact, I would have chosen to use an even wider aperture if possible, to make the background MORE blurry, rather than sharper - as that concentrate's the viewer's eye directly onto the subject, rather than be distracted by the background.

A polarizer would have avoided the reflection of the surrounding trees in Duck photo, but i intentionally left them as the main image is not disturbed by that. Also for me it looked better with the reflection